The ideal protein profile was developed by Agricultural Research council (1981) and was originally based on the lean tissue component of the pig. Maintenance requirement was then introduced by Fuller et al(1989) but ideal protein profile was still considered to have a constant ratio between all essential amino acids through the life cycle of the pig. However, the maintenance proportion for certain amino acids, such as the sulphur amino acids (SAA), may change as the pig grows. Hence, methionine and cysteine requirements are dependent on the relative balance of maintenance to protein accretion which is based on the protein deposition rate. Therefore, the objective of this study was to determine the relationship between true ileal digestible methionine and cysteine levels in feed and the ideal protein profile during the growing phase of superior genotype pigs.